Pyrenoid-core CO2-evolving machinery is essential for diatom photosynthesis in elevated CO2.
In: Plant physiology, Jg. 193 (2023-11-22), Heft 4, S. 2298-2305
academicJournal
Zugriff:
Marine diatoms are responsible for up to 20% of the annual global primary production by performing photosynthesis in seawater where CO2 availability is limited while HCO3- is abundant. Our previous studies have demonstrated that solute carrier 4 proteins at the plasma membrane of the diatom Phaeodactylum tricornutum facilitate the use of the abundant seawater HCO3-. There has been an unconcluded debate as to whether such HCO3- use capacity may itself supply enough dissolved inorganic carbon (DIC) to saturate the enzyme Rubisco. Here, we show that the θ-type carbonic anhydrase, Ptθ-CA1, a luminal factor of the pyrenoid-penetrating thylakoid membranes, plays an essential role in saturating photosynthesis of P. tricornutum. We isolated and analyzed genome-edited mutants of P. tricornutum defective in Ptθ-CA1. The mutants showed impaired growth in seawater aerated with a broad range of CO2 levels, from atmospheric to 1%. Independently of growth CO2 conditions, the photosynthetic affinity measured as K0.5 for DIC in mutants reached around 2 mm, which is about 10 times higher than K0.5[DIC] of high-CO2-grown wild-type cells that have repressed CO2-concentrating mechanism levels. The results clearly indicate that diatom photosynthesis is not saturated with either seawater-level DIC or even under a highly elevated CO2 environment unless the CO2-evolving machinery is at the core of the pyrenoid.
Competing Interests: Conflict of interest statement. The authors have no conflict of interest to declare.
(© American Society of Plant Biologists 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
Titel: |
Pyrenoid-core CO2-evolving machinery is essential for diatom photosynthesis in elevated CO2.
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Autor/in / Beteiligte Person: | Shimakawa, G ; Okuyama, A ; Harada, H ; Nakagaito, S ; Toyoshima, Y ; Nagata, K ; Matsuda, Y |
Zeitschrift: | Plant physiology, Jg. 193 (2023-11-22), Heft 4, S. 2298-2305 |
Veröffentlichung: | <May 2001->: [Rockville, MD] : American Society of Plant Biologists ; <i>Original Publication</i>: Lancaster, Pa., American Society of Plant Physiologists., 2023 |
Medientyp: | academicJournal |
ISSN: | 1532-2548 (electronic) |
DOI: | 10.1093/plphys/kiad475 |
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